1. Field of the Invention
The present invention relates to an adapter table apparatus having sensor function for fixing a work-piece that is used for positioning or centering for compact machine tool with a vertical main spindle.
2. Description of the Prior Art
A centering bar in which a measuring terminal eccentrically rotates until contacting a work-piece has been generally provided as a device for precisely performing positioning or centering in a machine tool. An operator visually confirms a moment when convergence of eccentric rotation and slice occur. Such position is determined as a reference. Even a skilled operator cannot easily and instantaneously catch a convergence state of such measuring terminal.
A touch sensor for automatic fine detection and an light emission alarm type centering bar have been provided as attempts to automate confirmation of the state of the centering bar. In accordance with the touch sensor, the moment when eccentrically rotating centering bar contacts a work-piece is electrically detected. Thus, a structure is highly complicated and extremely expensive device is provided.
In accordance with the light emission alarm type centering bar, when the centering bar contacts the work-piece, a conducting circuit from a main spindle via a machine main body to a stock vice is closed. Then, an LED is emitted and a buzzer rang. Attention must be paid to detect the moment of contact by such signal. In the electrically conducting circuit of the machine, a contact resistance such as a ball bearing of the main spindle or a stock vice supporting mechanism may be varied depending on a type of machine or a usage state. Further, as a contact detection circuit, a battery, light emission means and sound means are incorporated into the centering bar, the centering bar becomes a large size and cannot be applied to a compact machine.
Centering of work-piece or positioning of origin especially when one product is manufactured by a compact milling machine or a drilling machine is performed as follows. Namely, the work-piece is marked at any portion thereof and then centering or positioning is performed by using a gauge, a dial gauge, a digital scale or a score by the naked eye. Alternatively, a tool is rotated and the tool contacts a side surface of work-piece. A reference position is determined by a change of sound at this moment. In order to compensate for inaccuracy, trial cutting or milling is performed. Thus, additional labor and cost are required.